University of Texas at AustinMichigan Technological University 1 Evaluation of Alternative Reaction Pathways Chapters 7 and 8 David T. Allen Department of Chemical Engineering University of Texas at Austin Modified by Robert Hesketh, Rowan University

University of Texas at AustinMichigan Technological University 2 Module 3: Hierarchical design process for pollution prevention

University of Texas at AustinMichigan Technological University 3 l Guiding principles for reactions »Simplicity »Safety »High yield and selectivity »High energy and atom efficiency »Use of renewable resources »Recyclable reagents and raw materials Module 3: Green Chemistry - Ch 7

University of Texas at AustinMichigan Technological University 4 l Important considerations »Human / ecosystem health properties –Bioaccumulative? –Persistent? –Toxic? –Global warming, Ozone depletion, Smog formation? –Flammable or otherwise hazardous? –Renewable or non renewable resource? »Life cycle environmental burdens? - Ch 13, 14 Module 3: Feedstocks and solvents

University of Texas at AustinMichigan Technological University 5 Module 3: Alternative choices: raw materials Benzene fossil fuel source carcinogenic Glucose renewable source non-toxic

University of Texas at AustinMichigan Technological University 6 Module 3: Alternative choices: Solvents Supercritical CO 2 Non-toxic, non-flammable, renewable sources Water as alternative solvent (as a co-solvent with an alcohol) Selectivity enhancement with SC CO 2 Reaction rate enhancements

University of Texas at AustinMichigan Technological University 7 Module 3: Synthesis pathways

University of Texas at AustinMichigan Technological University 8 Module 3: Atom and Mass Efficiency: magnitude of improvements possible Atom Efficiency - the fraction of starting material incorporated into the desired product - C 6 H 5 -OH+ NH 3  C 6 H 5 -NH 2 + H 2 O Carbon - 100% Hydrogen - 7/9 x 100 = 77.8% Oxygen - 0/1 x 100 = 0% Nitrogen - 100% Mass Efficiency (Basis 1 mole of product) C 6 H 5 -OH+ NH 3  C 6 H 5 -NH 2 + H 2 O Mass in Product = (6 C) (12) + (7 H) x (1) + (0 O) x 16) + (1 N) x (14) = 93 grams Mass in Reactants = (6 C) (12) + (9 H) x (1) + (1 O) x 16) + (1 N) x (14) = 111 grams Mass Efficiency = 93/111 x 100 = 83.8%

University of Texas at AustinMichigan Technological University 9 Module 3: Software exploration Green Chemistry Expert System TOPIC AREAS Green Synthetic Reactions - search a database for alternatives Designing Safer Chemicals - information on chemical classes Green Solvents/Reaction Conditions - alternative solvents / uses - solvent properties

University of Texas at AustinMichigan Technological University 10 Module 3: Software demonstration Green Chemistry Expert System search Green Synthetic Reactions for adipic acid references

University of Texas at AustinMichigan Technological University 11 Module 3: Adipic Acid Synthesis Traditional vs. New Traditional Route - from cyclohexanol/cyclohexanone Cu (.1-.5%) C 6 H 12 O+ 2 HNO H 2 O C 6 H 10 O 4 + (NO, NO 2, N 2 O, N 2 ) V (.02-.1%) 92-96% Yield of Adipic Acid Carbon - 100% Oxygen - 4/9 x 100 = 44.4% Hydrogen - 10/18 x 100 = 55.6% Nitrogen - 0% Product Mass = (6 C)(12) + (10 H)(1) + (4 O)(16) = 146 g Reactant Mass = (6 C)(12) + (18 H)(1) + (9 O)(16) + (2 N)(14) = 262 g Mass Efficiency = 146/262 x 100 = 55.7% global warming ozone depletion hazardous Davis and Kemp, 1991, Adipic Acid, in Kirk-Othmer Encyclopedia of Chemical Technology, V. 1,

University of Texas at AustinMichigan Technological University 12 New Route - from cyclohexene Na 2 WO 4 2H 2 O (1%) C 6 H H 2 O 2 C 6 H 10 O H 2 O [CH 3 (n-C 8 H 17 ) 3 N]HSO 4 (1%) 90% Yield of Adipic Acid Carbon - 100% Oxygen - 4/8 x 100 = 50% Hydrogen - 10/18 x 100 = 55.6% Product Mass = (6 C)(12) + (10 H)(1) + (4 O)(16) = 146 g Reactant Mass = (6 C)(12) + (18 H)(1) + (8 O)(16) = 218 g Mass Efficiency = 146/218 x 100 = 67% Module 3: Adipic Acid Synthesis Traditional vs. New Sato, et al. 1998, A “green” route to adipic acid:…, Science, V. 281, 11 Sept

University of Texas at AustinMichigan Technological University 13 Module 3: Maleic Anhydride Synthesis Benzene vs Butane - Mass Efficiency Benzene Route (Hedley et al. 1975, reference in ch. 8) V 2 O 5 2 C 6 H O 2 2 C 4 H 2 O 3 + H 2 O + 4 CO 2 (air) MoO 3 95% Yield of Maleic Anhydride from Benzene in Fixed Bed Reactor Butane Route (VO) 2 P 2 O 5 C 4 H O 2 C 4 H 2 O H 2 O (air) 60% Yield of Maleic Anhydride from Butane in Fixed Bed Reactor Felthouse et al., 1991, “Maleic Anhydride,..”, in Kirk-Othmer Encyclopedia of Chemical Technology, V. 15,

University of Texas at AustinMichigan Technological University 14 Module 3: Maleic Anhydride Synthesis Benzene vs Butane - Summary Table 1 Rudd et al. 1981, “Petroleum Technology Assessment”, Wiley Interscience, New York 2 Chemical Marketing Reporter (Benzene and MA 6/12/00); Texas Liquid (Butane 6/22/00) 3 Threshold Limit Value, ACGIH - Amer. Conf. of Gov. Indust. Hyg., Inc., 4 Toxicity Weight, and 5 ChemFate Database - EFDB menu item

University of Texas at AustinMichigan Technological University 15 Module 3: Maleic Anhydride Synthesis Benzene vs Butane - Tier 1 Assessment Benzene Route Butane Route Where i is the overall stoichiometric coefficient of reactant or product i

University of Texas at AustinMichigan Technological University 16 Benzene Route Butane Route Module 3: Maleic Anhydride Synthesis Benzene vs Butane - Tier 1 Assessment